The M9 motorway between Danesfort and Paulstown in Co Kilkenny is to close for a month as emergency road works need to be carried out.
It is understood the embankment has to be removed and the road structure fixed as a result of subsidence.
Kilkenny County Council's Director of Services John Mulholland said the embankment failed due to "an ingress of water".
Mr Mulholland said that the problems were first noticed shortly after the section of motorway opened in September 2010.
He added that the contractor is liable for the cost of the repair works and not the council.
There are traffic cones and signs currently on the stretch of road warning motorists to slow down.
The 19km stretch of motorway will be closed from junction seven (Paulstown) to junction nine (Danesfort) in both directions from 8 October.
